Method of manufacturing semiconductor device

ABSTRACT

To improve reliability of a semiconductor device, in a flip-chip bonding step, a solder material that is attached to a tip end surface of a projecting electrode in advance and a solder material that is applied in advance over a terminal (bonding lead) are heated and thereby integrated and electrically connected to each other. The terminal includes a wide part (a first portion) with a first width W 1  and a narrow part (a second portion) with a second width W 2.  When the solder material is heated, the thickness of the solder material arranged over the narrow part becomes smaller than the thickness of the solder material arranged in the wide part. Then, in the flip-chip bonding step, a projecting electrode is arranged over the narrow part and bonded onto the narrow part. Thus, the amount of protrusion of the solder material can be reduced.

CROSS-REFERENCE TO RELATED APPLICATION

The disclosure of Japanese Patent Application No. 2011-145431 filed onJun. 30, 2011 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND

The present invention relates to technologies for manufacturingsemiconductor devices, and in particular relates to a technologyeffectively applied to a semiconductor device in which a bump electrodeof a semiconductor chip is connected to a terminal of a substrate via asolder material.

Japanese Patent Laid-Open No. 2000-77471 (Patent Document 1) discloses amounting method (a flip-chip mounting method), in which a bump electrodeprovided in a semiconductor chip and containing gold is connected to abonding pad of a wiring substrate via a solder material.

SUMMARY

In the flip-chip mounting method, a projecting electrode (a bumpelectrode, a bump) is formed over a plurality of electrode pads of asemiconductor chip, respectively. Then, the projecting electrode isconnected to a terminal on a wiring substrate side via, for example, asolder material so as to connect the semiconductor chip to the wiringsubstrate electrically. This projecting electrode is formed by aball-bonding method that applies a wire-bonding technique, for example.Here, a metallic material containing gold (Au) as a principal componentis used (e.g., see Patent Document 1). The present inventor has beenstudying the techniques for reducing the manufacturing cost f thesemiconductor device that is manufactured by flip-chip bonding. As apart of that effort, the present inventor has studied a technology, inwhich the material of a projecting electrode is changed to a metallicmaterial containing copper (Cu), for example, less expensive than gold(Au), as a principal component, and as a result has found the followingproblems.

In the flip-chip mounting method using a solder material, the soldermaterial is applied onto a terminal on a wiring substrate side inadvance, and then a projecting electrode and the solder material arebrought into contact with each other and subjected to a reflow process(heat-treatment), thereby bonding the projecting electrode and thesolder material. Here, when the material of the projecting electrode iscopper (Cu), an oxide film is more likely formed in the surface of theprojecting electrode than in the case of gold (Au). Therefore, in abonding method, in which a solder material is simply applied onto aterminal on a wiring substrate side, the bonding strength decreases ascompared with the case of the projecting electrode containing gold.Then, the present inventor has studied a bonding method, in which asolder material is applied in advance onto a terminal on a wiringsubstrate side and to the surface of the projecting electrode,respectively.

In the case of the bonding method, in which a solder material is appliedin advance to the surface of a projecting electrode, because theoxidation of the surface of the projecting electrode containing copper(Cu), for example, can be prevented or suppressed by the soldermaterial, a decrease in the bonding strength between the solder materialand the projecting electrode can be suppressed. However, it has beenfound that if the solder material is applied in advance onto theterminal on a wiring substrate side and to the surface of a projectingelectrode, respectively, the quantity of the solder material between theprojecting electrode and the terminal will increase and the soldermaterial will protrude into the periphery of the bonding region betweenthe projecting electrode and the terminal. If the solder materialprotrudes into the periphery of the bonding region in this manner, thendepending on a distance between the adjacent terminals (or between theprojecting electrodes), the adjacent terminals may be electricallyconnected to each other via the protruded solder material and beshorted. That is, this causes degradation in the reliability of thesemiconductor device. In other words, the prevention of the adjacentterminals (or the projecting electrodes) from being shorted even if thesolder material protrudes results in a limiting factor in reducing thedistances between a large number of terminals and improving theintegration level of the terminals. That is, this results in a limitingfactor in achieving the enhanced functionality (or miniaturization) ofthe semiconductor device.

The present invention has been made in view of the above-describedproblems, and provides a technology of improving the reliability of asemiconductor device.

Moreover, another object of the present invention is to provide atechnology capable of reducing the manufacturing cost of a semiconductordevice.

The other objects and the novel features of the present invention willbecome clear from the description of the present specification and theaccompanying drawings.

The following explains briefly the outline of a typical invention amongthe present inventions disclosed in the present application.

That is, a method of manufacturing a semiconductor device according toan aspect of the present invention includes a flip-chip bonding step ofelectrically connecting, via a solder material, a plurality ofprojecting electrodes formed over the surface of the semiconductor chipand each having a first solder material attached to a tip end surfacethereof, and a plurality of bonding leads of a wiring substrate. Here,the bonding leads each include a first portion having a first width in aplan view and a second portion integrally formed with the first portionand having a second width smaller than the first width in a plan view.Moreover, a plurality of second solder materials is applied to thebonding leads of the wiring substrate in advance. Then, in the flip-chipbonding step, the semiconductor chip is disposed over the wiringsubstrate so that the projecting electrodes overlap with the secondportions of the bonding leads. Moreover, in the flip-chip bonding step,the second solder material is melted by applying heat to the secondsolder material.

The following explains briefly the effects obtained by the typicalinvention among the present inventions disclosed in the presentapplication.

That is, according to an aspect of the present invention, thereliability of a semiconductor device can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing an overall structure on a chip mountingsurface side of a semiconductor device of an embodiment of the presentinvention;

FIG. 2 is a cross sectional view along an A-A line of FIG. 1;

FIG. 3 is a plan view showing a front surface (surface facing a wiringsubstrate) side of the semiconductor chip shown in FIG. 1;

FIG. 4 is a plan view showing a chip mounting surface side of the wiringsubstrate, with the semiconductor chip shown in FIG. 1 removed;

FIG. 5 is a plan view showing a rear surface (a mounting surface) sideof the semiconductor device shown in FIG. 1;

FIG. 6 is an enlarged plan view showing a planar positional relationshipbetween a terminal and a projecting electrode in a B portion of FIG. 4;

FIG. 7 is an enlarged sectional view along a C-C line of FIG. 6;

FIG. 8 is an enlarged sectional view along a D-D line of FIG. 6;

FIG. 9 is an enlarged sectional view showing a state where a soldermaterial is applied in advance before connecting a projecting electrodeto the wiring substrate shown in FIG. 7;

FIG. 10 is an explanatory view showing an overview of the steps ofmanufacturing the semiconductor device of one embodiment of the presentinvention;

FIG. 11 is a plan view showing the overall structure of a wiringsubstrate prepared in a substrate preparation step shown in FIG. 10;

FIG. 12 is an enlarged sectional view along an E-E line of FIG. 11;

FIG. 13 is an explanatory view schematically showing an example of themethod of forming a solder material shown in FIG. 12;

FIG. 14 is an explanatory view that schematically shows an example of amethod of forming a solder material shown in FIG. 12 by using a methodother than the method shown in FIG. 13;

FIG. 15 is a plan view showing a semiconductor wafer prepared in a waferpreparation step shown in FIG. 10;

FIG. 16 is an enlarged sectional view showing the periphery of a padformed in a chip area of the semiconductor wafer shown in FIG. 15;

FIG. 17 is an enlarged sectional view showing a state where a projectingelectrode is formed over a plurality of pads shown in FIG. 16;

FIG. 18 is an enlarged sectional view showing a state where a soldermaterial is attached onto a tip end surface of the projecting electrodeshown in FIG. 17;

FIG. 19 is an enlarged sectional view showing a state where a mask shownin FIG. 18 is removed;

FIG. 20 is an enlarged sectional view showing a state where the soldermaterial shown in FIG. 19 is heated to be deformed into a dome shape;

FIG. 21 is an enlarged sectional view showing a state where asemiconductor chip is mounted over the wiring substrate shown in FIG.12;

FIG. 22 is an enlarged plan view showing a planar positionalrelationship between a projecting electrode and a terminal when thesemiconductor chip is disposed over the wiring substrate;

FIG. 23 is an enlarged sectional view along a C-C line of FIG. 22;

FIG. 24 is an enlarged sectional view along a D-D line of FIG. 22;

FIG. 25 is an enlarged sectional view showing a state where theopposingly arranged solder materials shown in FIG. 23 are brought intocontact with each other;

FIG. 26 is an enlarged sectional view showing a state where theopposingly arranged solder materials shown in FIG. 24 are brought intocontact with each other;

FIG. 27 is an enlarged sectional view showing a state where the soldermaterials in contact with each other shown in FIG. 25 are integrated;

FIG. 28 is an enlarged sectional view showing a state where the soldermaterials in contact with each other shown in FIG. 26 are integrated;

FIG. 29 is an enlarged sectional view showing a state where an underfillresin is supplied between the semiconductor chip and the wiringsubstrate shown in FIG. 21;

FIG. 30 is an enlarged sectional view showing a state where a solderball is bonded onto a plurality of lands after reversing the upper andlower sides of the wiring substrate shown in FIG. 29;

FIG. 31 is a plan view (bottom view) showing a state where amulti-patterned substrate shown in FIG. 29 is singulated;

FIG. 32 is an enlarged plan view showing a wiring substrate that is avariant of FIG. 22;

FIG. 33 is an enlarged sectional view along a C-C line of FIG. 32;

FIG. 34 is a plan view showing a semiconductor chip that is a variant ofFIG. 3;

FIG. 35 is an enlarged plan view showing a state where the semiconductorchip shown in FIG. 34 is mounted over the wiring substrate shown in FIG.32;

FIG. 36 is an enlarged sectional view along a C-C line of FIG. 35;

FIG. 37 is an enlarged plan view showing a state where the semiconductorchip shown in FIG. 34 is mounted to a wiring substrate that is anothervariant of FIG. 22;

FIG. 38 is an enlarged sectional view along a C-C line of FIG. 37;

FIG. 39 is an enlarged plan view showing a variant of FIG. 37;

FIG. 40 is an enlarged sectional view along a C-C line of FIG. 39;

FIG. 41 is an enlarged plan view showing a variant of the wiringsubstrate shown in FIG. 39; and

FIG. 42 is an enlarged plan view showing another variant of FIG. 39.

DETAILED DESCRIPTION Explanation of the Description Form, the BasicTerminology, and the Usage in the Present Application

In the present application, the embodiment will be described, dividedinto a plural sections or the like, if necessary for convenience. Exceptfor the case where it shows clearly in particular, they are not mutuallyindependent, and regardless of before or after the description, are eachpart of a single example, and one has relationships such as some detailsof another, or some or entire of another. Moreover, in principle, theduplicated description of a similar portion is omitted. Furthermore, inthe following embodiment, each element is not necessarily indispensableunless otherwise specially stated, or unless theoretically restricted toa specified number of the elements, or unless the context clearlydictates otherwise.

Similarly, when described as “X is constituted by A” and so on withregard to the material, the composition, or the like in the embodimentor the like, X including elements other than “A” shall not be excludedunless otherwise specially stated or unless the context clearly dictatesotherwise. For example, speaking of the component, “X is constituted byA” means “X containing A as a principal component” and soon. Forexample, it is needless to say that even referring to a “silicon member”or the like, it is not limited to pure silicon but includes a membercontaining a SiGe (silicon germanium) alloy, a multi-element alloycontaining silicon as a principal component, other additives, and thelike. Moreover, even referring to gold plating, a Cu layer, nickelplating, or the like, it shall include not only a pure one but memberseach containing gold, Cu, nickel, or the like as a principal component,unless otherwise specially stated.

Furthermore, when referring to a specific numeric value or amount, theymay be greater or smaller than the specific number unless otherwisespecially stated, or unless theoretically restricted to a specifiednumber, or unless the context clearly dictates otherwise

Moreover, in each view of the embodiment, the same or similar portionwill be represented by the same or similar symbol or reference numeral,and the description thereof will not be repeated in principle.

Moreover, in the accompanying drawings, when the drawing becomesotherwise complicated or when a cross section is clearly discriminatedfrom a space, hatching or the like may be omitted even in a sectionalview. In this regard, when clear from the description or the like, theoutline of a background may be omitted even if it is a planarly closedhole. Furthermore, even if it is not a cross section, in order toclarify that it is not a space or in order to clarify the boundary of aregion, hatching or a dot pattern may be applied.

<Semiconductor Device>

FIG. 1 is a plan view showing an overall structure on a chip mountingsurface side of a semiconductor device of an embodiment of the presentinvention, and FIG. 2 is a cross sectional view along an A-A line ofFIG. 1. Moreover, FIG. 3 is a plan view showing a front surface (surfacefacing a wiring substrate) side of the semiconductor chip shown inFIG. 1. FIG. 4 is a plan view showing a chip mounting surface side of awiring substrate with the semiconductor chip shown in FIG. 1 removed.FIG. 5 is a plan view showing a rear surface (mounting surface) side ofthe semiconductor device shown in FIG. 1. Note that, in FIG. 2 to FIG.5, in order to make it easy to see the shape of a pad 2 d or a terminal11 which a semiconductor device 1 of the embodiment includes, the planardimensions of each of a plurality of pads 2 d or terminals 11 are shownlarger than the dimensions that are illustratively described below.

As shown in FIG. 1, the semiconductor device 1 of the embodimentincludes: a semiconductor chip 2; and a wiring substrate (base,interposer) 3, i.e., a base in which the semiconductor chip 2 ismounted, electrically connected to the semiconductor chip 2.

The semiconductor chip 2 includes a front surface 2 a (see FIG. 2, FIG.3) and a rear surface 2 b (see FIG. 1, FIG. 2) positioned on theopposite side of the front surface 2 a, the front surface 2 a and therear surface 2 b each forming a quadrangle in a plan view. For example,in an example shown in FIG. 3, the planar shape of the semiconductorchip 2 is a square, one side of which has the length of approximately 5mm. Moreover, the semiconductor chip 2 includes a side face 2 c (seeFIG. 2) positioned between the front surface 2 a and the rear surface 2b. Moreover, the semiconductor chip 2 includes a semiconductor substrate(the illustration is omitted) constituted by silicon, for example, and aplurality of semiconductor elements (the illustration is omitted), suchas a transistor, is formed in the major surface (element formingsurface) of the semiconductor substrate. Over the major surface of thesemiconductor substrate, wiring layer (the illustration is omitted)including a plurality of wirings and an insulating film isolatingbetween the wirings are stacked. The wirings of the wiring layer areelectrically connected to the semiconductor elements, respectively, toconstitute an integrated circuit. Moreover, in the front surface 2 a(see FIG. 3) of the semiconductor chip 2, the pads (electrode pads,bonding pads, chip electrodes) 2 d are formed. The pads 2 d are formedin the top layer of the wiring layers stacked over the semiconductorsubstrate, and are electrically connected to the semiconductor elementsvia the wirings of the wiring layer. Moreover, the front surface 2 a ofthe semiconductor chip 2 is covered with an insulating film, such assilicon oxide (SiO₂), while over the pads 2 d, an opening portion isformed in the insulating film covering the front surface 2 a. Then, inthe opening portion, the pad 2 d is exposed from the insulating film. Inthis manner, the pads 2 d formed in the front surface 2 a of thesemiconductor chip 2 are electrically connected to the semiconductorelements which the semiconductor chip 2 includes, and serve as anexternal terminal (electrode) of the semiconductor chip 2, respectively.

In the embodiment, for example, as shown in FIG. 3, the pads 2 d arearranged along four side faces (sides) 2 c of the semiconductor chip 2,respectively. The front surface 2 a of the semiconductor chip 2 ispartitioned into a main circuit forming region (logic circuit formingregion) where a main circuit (core circuit), such as a logic circuit, isformed, and an input/output terminal forming region (I/O region) wherethe pads 2 d are arranged. In the example shown in FIG. 3, the maincircuit forming region is formed in the center of the front surface 2 a,and the input/output terminal forming region is arranged so as tosurround the main circuit forming region. By partitioning the maincircuit forming region from the input/output terminal forming region inthis manner, even if, for example, a stress is generated in the pads 2d, the influence on the main circuit can be suppressed. Moreover, theinput/output terminal forming regions are put together in the peripheralportion of the front surface 2 a, so that the number of the pads 2 dthat are external terminals can be increased, and the area of the maincircuit forming region can be increased. In the embodiment, along fourside faces 2 c of the semiconductor chip 2, the pads 2 d are arranged inmultiple rows (two rows in FIG. 3), respectively. In other words, thesemiconductor chip 2 includes a plurality of first row pads 2 d 1arranged along the side face 2 c and a plurality of second row pads 2 d2 arranged between the first row pads 2 d 1 and the side face 2 c. Notethat, in the embodiment, the first row pads 2 d 1 and the second rowpads 2 d 2 are arranged outside the main circuit forming region (theillustration is omitted), but in the case where a configuration capableof relaxing the stress is employed for the pad 2 d or in the case wherethe stress is not considered, the first row pad 2 d 1, for example, maybe arranged inside the main circuit forming region. The first row pad 2d 1 and the second row pad 2 d 2 are provided corresponding to each ofthe four side faces 2 c of the semiconductor chip 2. By arranging thepads 2 d in multiple rows, respectively, along the side face 2 c in thismanner, the number of pads 2 d can be increased further than the casewhere they are arranged in one row. In this manner, when the pads 2 dare arranged in multiple rows, as shown in FIG. 3, the so-calledstaggered arrangement, in which the first row pads 2 d 1 and the secondrow pads 2 d 2 are alternately arranged along the side face 2 c, ispreferable. By arranging the pads 2 d in a staggered manner, a wiring 2e (see FIG. 8 described later) can be arranged between the adjacentfirst row pads 2 d 1 to connect to the second row pad 2 d 2electrically. In other words, the first row pad 2 d 1 can be arrangedbetween the wirings connected to the second row pad 2 d 2. Therefore, anincreased efficiency of the wiring layout (a reduction in the pitch)over the major surface of the semiconductor chip 2 can be achieved, sothat the number of the pads 2 d that are external terminals can beincreased and the area of the main circuit forming region can beincreased.

As shown in FIG. 1 and FIG. 2, the semiconductor chip 2 is mounted tothe wiring substrate 3. The wiring substrate 3 includes an upper surface(a chip mounting surface, a front side) 3 a (see FIG. 2, FIG. 4) and alower surface (a mounting surface, a rear surface) 3 b (see FIG. 2, FIG.5) positioned on the opposite side of the upper surface 3 a, the uppersurface and the lower surface each forming a quadrangle in a plan view.For example, in the example shown in FIG. 3, the planar shape of thewiring substrate 3 is a square, one side of which has the length ofapproximately 7 mm to 8 mm. Moreover, the wiring substrate 3 includes aside face 3 c (see FIG. 2) positioned between the upper surface 3 a andthe lower surface 3 b. As shown in FIG. 4, a plurality of terminals(bonding leads) 11 is arranged in the upper surface 3 a of the wiringsubstrate 3. More specifically, the wiring substrate 3 includes aninsulating layer (a core layer, a core material) 15. In an upper surface15 a of the insulating layer 15, a conductor pattern including theterminals 11 and a wiring connected to the terminal 11, and constitutedby, for example, copper (Cu), the conductor pattern, is formed. Theconductor pattern is covered with a solder resist film (an insulatingfilm, a protection film) 16 formed over the upper surface 15 a. In thesolder resist film 16, an opening portion 16 a is formed at a positionwhere the terminals 11 are arranged, and the terminals 11 are exposedfrom the solder resist film 16 in the opening portion 16 a. In a planview, the terminals 11 are arranged at a position where they overlapwith the pads 2 d (see FIG. 3) of the semiconductor chip 2. Therefore,in the embodiment, along each side (each side of the chip mountingportion forming a quadrangle in a plan view) of the chip mounting regionthat is a region overlapping with the semiconductor chip 2, theterminals 11 are arranged, respectively. In the chip mounting portion,also in the embodiment, along each side of the chip mounting region thatis a region overlapping with the semiconductor chip 2, the pads 2 d arearranged in multiple rows (two rows in FIG. 4), respectively. In otherwords, the upper surface 3 a of the wiring substrate 3 includes aplurality of first row terminals (first row bonding leads) 11 a arrangedalong each side of the chip mounting region and a plurality of secondrow terminals (second row bonding leads) 11 b arranged between the firstrow terminals 11 a and each side of the chip mounting region.Furthermore, in other words, the terminals include the first rowterminals 11 a electrically connected to the first row pads 2 d 1 andthe second row terminals 11 b electrically connected to the second rowpads 2 d 2. Moreover, the first row terminal 11 a and the second rowterminal 11 b are arranged at a position, where they face the pad 2 d(see FIG. 3) of the semiconductor chip 2, respectively, and thereforethey are arranged in a staggered manner corresponding to the arrangementof the pads 2 d.

On the other hand, as shown in FIG. 5, in the lower surface 3 b of thewiring substrate 3, a plurality of lands (external terminals) 12 thatare the external terminals of the semiconductor device 1 is arranged. Aplurality of solder balls (mounting terminals, bonding material) 13 isbonded to the lands 12. More specifically, as shown in FIG. 2, thewiring substrate 3 includes an insulating layer (a core layer, a corematerial) 15. In a lower surface 15 b of the insulating layer 15, aconductor pattern including the lands 12 and a wiring connected to thelands 12 and constituted by, for example, copper (Cu) is formed. Theconductor pattern is covered with a solder resist film (an insulatingfilm, a protection film) 17 that is formed so as to cover the lowersurface 15 b. In the solder resist film 17, an opening portion 17 a isformed at a position where the land 12 is arranged, and the lands 12 areexposed from the solder resist film 17 in the opening portion 17 a.Moreover, the solder ball 13 bonded to the land 12 is of a conductivebonding material which, in mounting the semiconductor device 1 to anon-illustrated mounting substrate, electrically connects the terminalson the mounting substrate side to the lands 12. Moreover, as shown inFIG. 5, in a plan view, the lands 12 and the solder balls 13 arearranged in a matrix (in an array). As with the semiconductor device 1,a package, in which the lands 12 (or solder balls 13) that are externalterminals are arranged in a matrix in the mounting surface, is called anarea array type semiconductor device. In the area array typesemiconductor device 1, because the lower surface 3 b of the wiringsubstrate 3 serving as the mounting surface can be effectively utilizedas an arranging space for external terminals, the number of terminalscan be increased while suppressing an increase in the mounting area.

Moreover, as schematically shown in FIG. 2, the terminals 11 of thewiring substrate 3 are electrically connected to a plurality of lands 12via a plurality of wirings 14 that electrically connects the uppersurface 3 a side to the lower surface 3 b side of the wiring substrate3. In this manner, the wiring substrate 3, in electrically connectingnon-illustrated mounting substrate to the semiconductor chip 2, servesas an interposer that relays between the semiconductor chip 2 and themounting substrate. Note that, in FIG. 2, although the wirings 14 areschematically shown using a straight line, respectively, the wirings 14include a wiring routed in each wiring layer which the wiring substrate3 includes, and an interlayer wiring (a via wiring) electricallyconnecting between a plurality of wiring layers which the wiringsubstrate 3 includes. Moreover, in FIG. 2, the wiring substrate 3including four layers of wiring layers (a total of four layers: thefirst layer in the upper surface 15 a of the insulating layer 15; thesecond layer and the third layer between the upper surface 15 a and thelower surface 15 b; and the fourth layer in the lower surface 15 b) isshown as an example, but the number of wiring layers is not limited tofour and can be modified according to the number of terminals or to thewiring layout.

In the embodiment, as shown in FIG. 2, the semiconductor chip 2 ismounted over the wiring substrate 3 by the so-called flip-chip mountingmethod (face-down mounting method), with the front surface 2 a of thesemiconductor chip 2 facing the upper surface 3 a of the wiringsubstrate 3. The terminals 11 are arranged at positions facing the pads2 d of the semiconductor chip 2, and are electrically connected to thepads 2 d via a plurality of projecting electrodes (columnar electrodes)4 and the solder material 5 as shown in FIG. 2. Moreover, thesemiconductor chip 2 is fixed onto the upper surface 3 a of the wiringsubstrate 3 via the projecting electrodes 4 and the solder material 5.That is, the projecting electrodes 4 formed over the pad 2 d are bondedto the terminal 11 via the solder material 5, so that the semiconductorchip 2 is fixed onto the wiring substrate 3 and also is electricallyconnected to the wiring substrate 3.

The projecting electrode 4 of the embodiment is constituted by, forexample, copper (Cu), and is a columnar electrode forming a cylindricalshape. Note that, the shape of the projecting electrode 4 is notrestricted only to the cylindrical shape, but may be a rectangularcolumnar shape. Usually, as the constituent material of a projectingelectrode bonded to the electrode pad of a semiconductor chip, gold (Au)other than copper (Cu) may be used, but by using the projectingelectrode 4 constituted by copper (Cu) as with the embodiment 4, thematerial cost can be significantly reduced. Moreover, the soldermaterial 5 and the solder ball 13 of the embodiment are constituted bythe so-called lead-free solder that does not essentially contain lead(Pb), and is constituted by, for example, only tin (Sn), a tin-Bis film(Sn—Bi), tin-silver (Sn—Ag), tin-silver-copper (Sn—Ag—Cu), or the like.Here, the lead-free solder means solders with the content of lead (Pb)equal to or less than 0.1 wt %, and this content is specified as thestandard of RoHS (Restriction of Hazardous Substances) Directive.

Moreover, between the front surface 2 a of the semiconductor chip 2 andthe upper surfaces 3 a of the wiring substrate 3, an underfill resin(sealant) 6 is arranged and the bonding portion between the pad 2 d andthe terminal 11 is sealed with the underfill resin 6. In this manner, bysealing the bonding portion between the pad 2 d and the terminal 11 withthe underfill resin 6, a stress generated in the periphery of thebonding portion between the pad 2 d and the terminal 11 can bedistributed and relaxed. However, the flip-chip mounting method is notlimited to the embodiment in which the underfill resin 6 is arrangedbetween the semiconductor chip 2 and the wiring substrate 3 as shown inFIG. 2, but can be applied, as a variant, to configurations in which theunderfill resin 6 is not arranged.

<Peripheral Structure of the Terminal Bonding Portion>

Next, the detailed structure in the periphery of the bonding portionbetween the pad 2 d and the terminal 11 shown in FIG. 2 is described.FIG. 6 is an enlarged plan view showing a planar positional relationshipbetween the terminal and the projecting electrode in a B portion of FIG.4. FIG. 7 is an enlarged sectional view along a C-C line of FIG. 6 andFIG. 8 is an enlarged sectional view along a D-D line of FIG. 6. FIG. 9is an enlarged sectional view showing a state where a solder material isapplied in advance before connecting the projecting electrode to thewiring substrate shown in FIG. 7.

As shown in FIG. 6, each of the terminals 11 includes a wide part(portion) 11 w having a width (length in a direction intersecting thedirection in which the terminal 11 extends) W1 in a plan view and anarrow part (portion) 11 n having a width (length in the directionintersecting the direction in which the terminal 11 extends) W2 smallerthan the width W1 in a plan view, the narrow part (portion) beingintegrally formed with the wide part (portion) 11 w. In the embodiment,the width W1 of the wide part (portion) 11 w is nearly equal to a width(diameter in plan view) WB of the projecting electrode 4, and isapproximately 30 μm, for example. On the other hand, the width W2 of thenarrow part (portion) 11 n is smaller (narrower) than the width W1, andis approximately 20 μm, for example. Then, the projecting electrodes 4(pads 2 d) are arranged at positions where they overlap with the narrowpart (portion) 11 n of the terminals 11, respectively, and are connectedto the terminals 11 via the solder material 5 shown in FIG. 7 and FIG.8.

From a view point of increasing the closely contacted area between thesolder material 5 and the terminal 11 in a region facing the projectingelectrode 4, the projecting electrode 4 is preferably arranged at aposition where it overlaps with the wide part (portion) 11 w. However,in the embodiment, the projecting electrode 4 is arranged at a positionwhere it overlaps with the narrow part (portion) 11 n from the reasonsbelow. The projecting electrode 4 of the embodiment is constituted bycopper (Cu) that is easily oxidized as compared with gold (Au). Then, ifan oxide film is formed in the surface of the projecting electrode 4,the wettability of the solder material 5 will degrade, and therefore thebonding strength between the solder material 5 and the projectingelectrode 4 will decrease. For this reason, with the surface of theprojecting electrode 4 covered in advance with a solder material (asolder material serving as the raw material of the solder material 5),the projecting electrode 4 is subjected to a heat treatment (localreflow process) and bonded to the terminal 11. On the other hand, theterminal 11 of the embodiment is constituted by copper (Cu) as describedabove. Therefore, as with the case of the projecting electrode 4, if anoxide film is formed in the surface of the terminal 11, the wettabilityof the solder material 5 will decrease and therefore the bondingstrength between the solder material 5 and the terminal 11 willdecrease. For this reason, with the surface of the terminal 11 coveredin advance with a solder material (a solder material serving as the rawmaterial of the solder material 5), the terminal is subjected to a heattreatment (local reflow process) and bonded to the projecting electrode4. In this manner, the bonding strength of the bonding portion betweenthe projecting electrode 4 and the terminal 11 can be improved bybonding the projecting electrode 4 to the terminal 11, with the rawmaterial of the solder material 5 applied in advance to the surface ofthe projecting electrode 4 and the surface of the terminal 11,respectively.

However, when the projecting electrode 4 is bonded to the terminal 11,with a material serving as the raw material of the solder material 5applied in advance to the surface of the projecting electrode 4 and thesurface of the terminal 11, respectively, the quantity of the soldermaterial will increase in order to reliably cover the surface of theterminal 11 and the projecting electrode 4. In particular, when a soldermaterial serving as the raw material of the solder material 5 is appliedto the surface of the terminal 11 by printing (the detail is describedlater), the thickness thereof becomes approximately 15 μm to 18 μm. Ithas been found that for this reason, the quantity of the solder material5 for integrally forming the solder material applied to each of theprojecting electrode 4 and the terminal 11 will increase, and if a gapbetween the surface (the tip end surface 4 s) of the projectingelectrode 4 and the surface (the upper surface) of the terminal 11becomes narrow by mounting the semiconductor chip 2, then a part of thesolder material 5 interposed between the surface (the tip end surface 4s) of the projecting electrode 4 and the surface (the upper surface) ofthe terminal 11 protrudes into the periphery of the bonding region (forexample, between the adjacent projecting electrodes 4 shown in FIG. 8).If the solder material 5 protrudes into the periphery of the bondingregion, then depending on the distance between the adjacent terminals 11(or between the projecting electrodes 4), the adjacent terminals 11 canbe electrically connected and shorted to each other via the protrudedsolder material 5. That is, this causes degradation in the reliabilityof the semiconductor device. In other words, the prevention of theadjacent terminals 11 (or the projecting electrodes 4) from beingshorted even if the solder material protrudes results in a limitingfactor in reducing the distances between a large number of terminals andimproving the integration level of the terminals. That is, this resultsin a limiting factor in achieving the enhanced functionality (orminiaturization) of the semiconductor device.

As the countermeasure for the above-described problem, the followingtechniques can be contemplated. One technique, in which the surface ofthe terminal 11 constituted by copper (Cu) is covered with, for example,a metal film constituted by a material, such as gold (Au), that is moredifficult to be oxidized than copper (Cu), may be contemplated in orderto prevent or suppress the formation of an oxide film in the surface ofthe terminal 11. In this case, even if a solder material serving as theraw material of the solder material 5 is not applied to the surface ofthe terminal 11 in advance, a decrease in the wettability of the soldermaterial 5 in the surface of the terminal 11 can be suppressed. However,in this case, because the terminal 11 and the projecting electrode 4 arebonded to each other only using the solder material applied to theprojecting electrode 4, the quantity of the solder material 5 becomes inshort, thus causing a decrease in the bonding strength. Moreover, whenthe quantity of the solder material 5 is small, the solder material 5will flow into the periphery of the bonding portion during a reflowprocess, thus causing a conduction failure between the projectingelectrode 4 and the terminal 1. Another technique, in which the soldermaterial serving as the raw material of the solder material 5 is appliedto (formed in) the surface of the terminal 11 by plating, may becontemplated. For example, with an electrolysis plating method, thesolder material (solder film) serving as the raw material of the soldermaterial 5 can be applied with a thickness of approximately 5 μm.However, in order to apply (form) the solder material by electrolysisplating, each of the terminals 11 needs to be connected to a wiring forfeeding a current (a power supply wiring). That is, there is a need tosecure a space for arranging the power supply wiring for electrolysisplating in the wiring substrate 3, and thus the miniaturization of thewiring substrate becomes difficult. In addition, the degree of freedomof the layout of the wiring 14 connected to the terminal 11 of thewiring substrate 3 will decrease. Moreover, in the case where the soldermaterial is applied (formed) by electroless plating, the power supplywiring does not have to be arranged but an unevenness easily occurs inthe applied solder material. In other words, the solder material may notbe formed at a position facing the projecting electrode 4 of theterminal 11. Moreover, in the electroless plating method, because theplating film is deposited by reduction, the terminal 11 constituted bycopper (Cu) is corroded by the used plating liquid and when theprojecting electrode 4 is bonded to the narrow part (portion) 11 n ofthe terminal 11, as with the embodiment, a bonding failure will easilyoccur.

Then, the present inventor has studied in light of the above-describedproblem and found a configuration shown in FIG. 6 to FIG. 8. That is,each of the terminals 11 includes the wide part (portion) 11 w havingthe width W1 in a plan view and the narrow part (portion) 11 n havingthe width W2 smaller than the width W1 in a plan view, the narrow part(portion) 11 n being integrally formed with the wide part (portion) 11w. Then, the projecting electrode 4 is arranged at a position where itoverlaps with the narrow part (portion) 11 n, and is bonded via thesolder material 5. In other words, the bonding region for bonding theprojecting electrode 4 overlaps with the narrow part (portion) 11 n ofthe terminal 11. In the technique of applying a solder material to thesurfaces of the terminals 11 by printing, a solder component and asolder paste containing a flux component (component for activating thesolder component), or a large number of solder particles (solder powder)and flux paste (paste containing a flux component) are applied to thesurface of the terminal 11. Then, if a heat treatment (reflow process)is carried out with a flux component and a solder composition in contactwith each other, the solder component will melt and be integrated withthe flux component. At this time, the melted solder component (meltedsolder), under the influence of a surface tension of the melted solder,deforms so as to be a physically stable shape.

Here, when the planar shape of the terminal 11, to which the soldermaterial is applied, is not a simple shape, such as a simple square, themelted solder will, under the influence of a surface tension, deform inaccordance with the shape of the terminal 11. That is, in a metallicpattern extending in a certain direction, when a portion with a widewidth and a portion with a narrow width are present, the melted soldertends to easily gather toward the portion with a wide width. Whenapplied to an example shown in FIG. 6, a lot of melted solder gathers tothe wide part (portion) 11 w, and a dome-shaped (hemispherical) soldermaterial (solder lump) 5 a 1 is formed following the shape of the widepart (portion) 11 w, as shown in FIG. 9. On the other hand, over thenarrow part (portion) 11 n shown in FIG. 6, particularly in a regionadjacent to the wide part (portion) 11 w, because the melted soldermoves toward the wide part (portion) 11 w, the quantity of a soldermaterial (solder film) 5 a 2 formed by the melted solder becomes lessthan the wide part (portion) 11 w, as shown in FIG. 9. Then, when themelted solder is cooled and the residual substance and the like of theflux component are removed by cleaning, the solder material (soldermaterial serving as the raw material of the solder material 5) isapplied (formed) onto the terminal 11, with the shape, which is formedby a surface tension of the melted solder, retained. That is, among thesolder material 5 a applied (formed) onto the surface of the terminal 11in advance, the quantity (thickness) of the solder material 5 a 2provided in the narrow part (portion) 11 n becomes smaller (thinner)than the quantity (thickness) of the solder material 5 a 1 provided inthe wide part (portion) 11 w. In other words, in the embodiment, each ofthe terminals 11 has a shape including the wide part (portion) 11 w andthe narrow part (portion) 11 n, so that, for example, even if thetechnique of applying the solder material 5 a by printing is used, thesolder material 5 a 2 can be stably formed thin. For example, in theembodiment, the thickness of the solder material 5 a 1 (distance fromthe upper surface of the terminal 11 to the highest point of the soldermaterial 5 a 1) is equal to or greater than 10 μm. However, when thesolder material 5 a is applied by printing, the thickness of the soldermaterial 5 a 1 is in particular preferably set equal to or greater than20 μm. On the other hand, the thickness of the solder material 5 a 2(distance from the upper surface of the terminal 11 to the highest pointof solder material 5 a 2) is equal to or less than 7 μm. However, whenthe thickness of the solder material 5 a 1 is set equal to or greaterthan 20 μm, the thickness of the solder material 5 a 2 may become equalto or less than 10 μm.

Thus, according to the embodiment, the thickness of the solder material5 a 2 applied (formed) onto the narrow part (portion) 11 n can be stablythinned. For this reason, the projecting electrode 4 (see FIG. 7) isarranged over the solder material 5 a 2, which is formed thin, (that is,at a position where it overlaps with the narrow part 11 n) and is bondedto the solder material 5 a 2, so that the quantity of the soldermaterial 5 for connecting the terminal 11 to the projecting electrode 4can be controlled to a proper quantity, as shown in FIG. 7 and FIG. 8.Accordingly, a degradation in the reliability of the semiconductordevice 1 caused by the solder material 5 protruding into the peripheryof the bonding region can be prevented or suppressed. In other words,the reliability of the semiconductor device 1 can be improved. Moreover,in the embodiment, because the solder material 5 a can be stably formedby printing, the wiring for electrolysis plating (the power supplywiring) is not provided in the wiring substrate 3. Accordingly, thearrangement space of the power supply wiring and the periphery spacethereof can be omitted, and therefore the planar size of the wiringsubstrate 3 can be reduced. In other words, the mounting area of thesemiconductor device 1 can be reduced. Moreover, by not providing thepower supply wiring, the degree of freedom of the wiring layout designcan be improved. According to the embodiment, the printing method can beapplied as the method of applying the solder material 5 a, and thereforeeven if the wiring substrate is mass-produced, it can be stablymass-produced. In the case where the above-described technique isapplied, if the projecting electrode 4 is bonded to the solder material5 a 1 arranged over the wide part (portion) 11 w, among the soldermaterial 5 a shown in FIG. 9, then a part of the solder material 5 a 1will move to the projecting electrode 4 side, but most of the soldermaterial 5 a 1 will remain over the wide part (portion) 11 w as shown inFIG. 7. Accordingly, in the semiconductor device 1 of the embodiment towhich the above-described technique is applied, among the soldermaterial 5 for bonding the terminal 11 and the projecting electrode 4,the thickness of the solder material 5 w arranged on the wide part(portion) 11 w side from the bonding portion (a region sandwiched by thetip end surface 4 s and the terminal 11) between the solder material 5and the projecting electrode 4 becomes larger than the thickness of thesolder material 5 a 2 arranged on the narrow part (portion) 11 n sidefrom the bonding portion between the solder material 5 and theprojecting electrode 4 (on the opposite side of the wide part (portion)11 w). However, among the solder materials 5, the thickness of thesolder material arranged in the bonding portion (a region sandwiched bythe tip end surface 4 s and the narrow part 11 n) between the soldermaterial 5 and the projecting electrode 4 may become larger than thesolder material 5 w arranged over the wide part (portion) 11 w under theinfluence of a surface tension.

Note that, as a variant of the embodiment, even when the solder material5 a is formed by applying techniques other than the printing method, ifthe solder material applied onto the terminal 11 is subjected to a heattreatment and is melted, the melted solder will deform in accordancewith the shape of the terminal 11 as described above. Accordingly, evenin cases where, for example, the plating method (the electrolysisplating method or electroless plating method) is applied, when theplating film of a solder material is deposited with a thickness equal toor greater than approximately 10 μm, for example, it is effective toapply the above-described structure of the embodiment and melt thesolder material before bonding the projecting electrode 4, and form theshown in FIG. 9 solder material 5 a.

Moreover, from a view point of stably thinning the thickness of thesolder material 5 a 2, the widths of the wide part (portion) 11 w andthe narrow part (portion) 11 n provided in the terminal 11 may be set torelatively different widths, and therefore, for example, as a variant ofthe terminal 11 shown in FIG. 6, the width W1 of the wide part (portion)11 w may be set wider than the width (the diameter in a plan view) WB ofthe projecting electrode 4, thereby setting the width W2 of the narrowpart (portion) 11 n nearly equal to the width of the projectingelectrode 4. However, from a view point of reducing the planardimensions of the terminals 11, as shown in FIG. 6, it is preferablethat the width W1 of the wide part (portion) 11 w is set nearly equal tothe width WB of the projecting electrode 4 and that the width W2 of thenarrow part (portion) 11 n is set smaller than the width of theprojecting electrode 4. In this case, as shown in FIG. 8, a part of thetip end surface (the surface facing the upper surface 11 c of theterminal 11) 4 s of the projecting electrode 4 is arranged so as toprotrude to the outside of the terminal 11. Accordingly, from a viewpoint of suppressing a decrease in the bonding strength due to bondingthe projecting electrode 4 to a position where it overlaps with thenarrow part (portion) 11 n, the solder material 5 n is preferably formedso as to cover the upper surface 11 c and both side faces 11 d of theterminal 11. Because this can increase the contact area between thesolder material 5 n and the terminal 11, a decrease in the bondingstrength can be suppressed.

<Method of Manufacturing the Semiconductor Device>

Next, a method of manufacturing the semiconductor device of theembodiment is described. The semiconductor device 1 in the embodiment ismanufactured following a flow shown in FIG. 10. FIG. 10 is anexplanatory view showing an overview of the steps of manufacturing thesemiconductor device of the embodiment. The detail of each step will bedescribed below using FIG. 11 to FIG. 31.

<Substrate Preparation Step>

First, in a substrate preparation step shown in FIG. 10, a wiringsubstrate 20 shown in FIG. 11 and FIG. 12 is prepared. FIG. 11 is a planview showing the overall structure of the wiring substrate prepared inthe substrate preparation step shown in FIG. 10, and FIG. 12 is anenlarged sectional view along an E-E line of FIG. 11.

As shown in FIG. 11, the wiring substrate 20 prepared in this stepincludes a plurality of product forming regions 20 a inside a frameportion (frame body) 20 b. More specifically, the plurality (in FIG. 11,27 pieces) of product forming regions 20 a is arranged in a matrix. Thewiring substrate 20 is the so-called multi-patterned substrate thatincludes the product forming regions 20 a each corresponding to thewiring substrate 3 shown in FIG. 1 and a dicing line (a dicing area) 20c between the respective product forming regions 20 a. In this manner,by using a multi-patterned substrate including the product formingregions 20 a, the manufacturing efficiency can be improved.

Moreover, as shown in FIG. 12, in each product forming region 20 a, aconstituent member of the wiring substrate 3 described using FIG. 1 toFIG. 9 is formed. More specifically, the wiring substrate 20 includes aninsulating layer (a core layer, a core material) 15 having the uppersurface 15 a and the lower surface 15 b on the opposite side of theupper surface 15 a, the insulating layer 15 being constituted by resin,for example. Moreover, each product forming region 20 a of the wiringsubstrate 20 includes the terminals 11 arranged on the upper surface 3 aside, the lands 12 arranged on the lower surface 3 b side, and thewirings 14 for electrically connecting the terminals 11 and the lands12. Moreover, the portion over the upper surface and the portion underthe lower surface 15 b of the insulating layer 15 are covered with thesolder resist films 16 and 17, respectively, and in the opening portion16 a formed in the solder resist film 16, the terminals (bonding leads)11 are exposed from the solder resist film 16. In the embodiment, theterminals 11 are exposed in one opening portion 16 a. Moreover, in theopening portions 17 a formed in the solder resist film 17, the lands 12are exposed from the solder resist film 17, respectively. The conductorpatterns (the terminals 11, the lands 12, and the wirings 14) which thewiring substrate 20 includes are formed by a metallic materialcontaining copper (Cu) as a principal component, respectively. In theembodiment, as the technique for forming these conductor patterns, atechnique, such as a subtract process or a semi-additive process, isused. With such a process, as shown in FIG. 6, the shape of the terminal11 including: the wide part (portion) 11 w having the width (the lengthin the direction intersecting the direction in which the terminal 11extends) W1 in a plan view; and the narrow part (portion) 11 n havingthe width (the length in the direction intersecting the direction inwhich the terminal 11 extends) W2 smaller than the width W1 in a planview, the narrow part (portion) being integrally formed with the widepart (portion) 11 w, can be formed. Accordingly, the terminals 11, whichthe wiring substrate 20 prepared in the step includes, has a planarshape including the wide part (portion) 11 w and the narrow part(portion) 11 n as shown in FIG. 6.

Moreover, over the upper surface 11 c of the terminals 11, the soldermaterials 5 a are applied in advance. The solder material 5 a is the rawmaterial of the solder material 5 shown in FIG. 2, as described above.In the solder material 5 a, among the solder materials 5 a applied(formed) onto the surface of the terminal 11 in advance, the quantity(thickness) of the solder material 5 a 2 provided in the narrow part(portion) 11 n is applied (formed) so as to be smaller (thinner) thanthe quantity (thickness) of the solder material 5 a 1 provided in thewide part (portion) 11 w. In other words, the terminals 11 each includethe region (the narrow part 11n), in which the solder material (solderfilm) 5 a 2 is applied (formed) thin (e.g., with a thickness equal to orless than 7 μm), adjacent to the wide part (portion) 11 w. The soldermaterial 5 a is formed, for example, by printing, as described above.Hereinafter, a method of forming the solder material 5 a 2 by printingis described. FIG. 13 is an explanatory view that schematically shows anexample of the method of forming the solder material shown in FIG. 12,and FIG. 14 is an explanatory view that schematically shows an exampleof a method of forming the solder material shown in FIG. 12 by using amethod other than the method shown in FIG. 13.

In the method of forming the solder material shown in FIG. 13, first, inStep S1 (the substrate preparation step shown in FIG. 10), the wiringsubstrate 20 having the terminals 11 formed therein is prepared. Next,in Step 2 (a solder material application step shown in FIG. 10), asolder paste (solder material) Pss is applied (printed) onto theterminals 11. The solder paste Pss contains a solder component and aflux component for activating the solder component, and exhibitspaste-like properties at room temperature. In the embodiment, instead ofindependently applying the solder paste Pss to each of the terminals 11,the solder paste Pss is applied so as to collectively cover theterminals 11. By employing such an application method, the applicationstep can be simplified. Next, in Step 3 (a heat treatment step shown inFIG. 10), a heat treatment (reflow process) is carried out to the solderpaste Pss to melt the solder component contained in the solder pastePss. Note that, the heating temperature at this time differs dependingon the melting point of the solder component, but when a tin-silver(Sn—Ag)-based lead-free solder is employed, the solder paste Pss isheated at 240° C. to 280° C., for example. In the step, a flux (fluxcomponent) FL contained in the solder paste Pss can improve thewettability of the melted solder Ms with respect to the terminal 11 byactivating the solder component of the solder paste Pss. Moreover, inthe step, the melted solder Ms, under the influence of a surfacetension, deforms so as to be a physically stable shape. Accordingly, aswith the solder material 5 a shown in FIG. 9 or FIG. 12, a lot of meltedsolder Ms gathers onto the wide part (portion) 11 w (see FIG. 13). As aresult, the thickness of the melted solder Ms over the narrow part(portion) 11 n shown in FIG. 13 can be stably thinned, with a thicknessequal to or less than 7 μm, for example. Next, in Step 4 (a cleaningstep shown in FIG. 10), the melted solder Ms is solidified by coolingthe melted solder Ms, thereby forming the solder material 5 a. Moreover,by cleaning the periphery of the terminal 11 and removing the residualsubstance of the flux FL remaining in the periphery of the soldermaterial 5 a, the wiring substrate 20 having the solder material 5 ashown in FIG. 12 formed therein can be obtained.

On the other hand, the method of forming the solder material shown inFIG. 14 is as follows. First, in Step S1 (the substrate preparation stepshown in FIG. 10) shown in FIG. 14, the wiring substrate 20 having theterminals 11 formed therein is prepared. Next, in Step S2 (the substratepreparation step shown in FIG. 10), the terminals 11 formed in thewiring substrate 20 are immersed into an agent and then dried so as toform an adhesive film NF in the surface (the upper surface and the sideface) of the terminal 11. Because the adhesive film NF is formed by achemical reaction between the metal in the surface of the terminal 11and the agent, the adhesive film NF can be formed in the exposed surface(the upper surface and the side face) of the terminal 11. Next, in StepS3 (the solder material application step shown in FIG. 10), a largenumber of solder particles (solder powder, solder material) Pws areapplied (printed) onto the terminals 11 and are stuck to the adhesivefilm NF. Because the adhesive film NF is selectively formed in thesurface of the terminal 11, even if the solder particles Pws arecollectively applied onto the terminals 11, the solder particle Pws willnot adhere to the upper surface 15 a of the insulating layer 15.Accordingly, the solder particles Pws can be selectively stuck onto theterminal 11. For this reason, as compared with the method shown in FIG.13, the quantity of the solder component adhering to the periphery ofthe terminal 11 can be reduced. Moreover, with the average particle sizeof the solder particle Pws, the quantity of the solder componentadhering to the periphery of the terminal 11 can be controlled. That is,if the average particle size of the solder particle Pws is reduced, thequantity of the solder component adhering to the periphery of theterminal 11 can be reduced. In contrast, if the average particle size ofthe solder particle Pws is increased, the quantity of the soldercomponent adhering to the periphery of the terminal 11 can be increased.Next, in Step S4 (the solder material application step shown in FIG.10), a paste (flux paste) containing the flux FL is applied (printed) soas to cover the terminals 11 and the solder particles Pws. The flux FLis applied in order to activate the solder particle (solder component)Pws and improve the wettability with respect to the terminal 11, andtherefore from a view point of simplifying the application step, theflux FL is collectively applied so as to cover the terminals 11, forexample. Next, in Step S5 (a heat treatment step shown in FIG. 10), aheat treatment (reflow process) is carried out to the solder particlePws to melt the solder component. Note that, the heating temperature atthis time differs depending on the melting point of the soldercomponent, but when a tin-silver (Sn—Ag)-based lead-free solder isemployed, the solder paste Pss is heated at 240° C. to 280° C. In thisstep, because the flux FL applied onto the solder particle Pws activatesthe solder component, the wettability of the melted solder Ms withrespect to the terminal 11 can be improved. Moreover, in this step, asdescribed above, the melted solder Ms, under the influence of a surfacetension, deforms so as to be a physically stable shape. Accordingly, aswith the solder material 5 a shown in FIG. 9 or FIG. 12, a lot of meltedsolder Ms gathers onto the wide part (portion) 11 w (see FIG. 13). Next,in Step S6 (a cleaning step shown in FIG. 10), the melted solder Ms issolidified by cooling the melted solder Ms, thereby forming the soldermaterial 5 a. Moreover, by cleaning the periphery of the terminal 11 andremoving the residual substance of the flux FL remaining in theperiphery of the solder material 5 a, the wiring substrate 20 having thesolder material 5 a shown in FIG. 12 formed therein can be obtained.

Note that, in the above-described methods of forming the solder material5 a, two methods, among the methods which the present inventor hasstudied, which may be particularly suitable, are exemplarily taken.Accordingly, it is needless to say that various modifications arepossible without departing from the scope and spirit of the presentinvention.

<Semiconductor Chip Preparation Step>

In a semiconductor chip preparation step shown in FIG. 10, theabove-described semiconductor chip 2 shown in FIG. 3 is prepared. FIG.15 is a plan view showing a semiconductor wafer prepared in the waferpreparation step shown in FIG. 10, and FIG. 16 is an enlarged sectionalview showing the periphery of a pad formed in a chip area of thesemiconductor wafer shown in FIG. 15. Moreover, FIG. 17 is an enlargedsectional view showing a state where a projecting electrode is formedover a plurality of pads shown in FIG. 16, FIG. 18 is an enlargedsectional view showing a state where a solder material is applied onto atip end surface of the projecting electrode shown in FIG. 17, FIG. 19 isan enlarged sectional view showing a state where a mask shown in FIG. 18is removed, and FIG. 20 is an enlarged sectional view showing a statewhere the solder material shown in FIG. 19 is deformed into a dome-likeshape by heating.

The semiconductor chip shown in FIG. 3 is manufactured as follows, forexample. First, in the wafer preparation step shown in FIG. 10, a wafer(semiconductor wafer) 25 shown in FIG. 15 is prepared. The wafer 25prepared in this step has the front surface 2 a with asubstantially-circular planar shape and the rear surface 2 b positionedon the opposite side of the front surface 2 a, as shown in FIG. 15.Moreover, the wafer 25 includes a plurality of chip areas (device areas)25 a, and each chip area 25 a corresponds to the semiconductor chip 2shown in FIG. 3. Moreover, between the adjacent chip areas 25 a, ascribe line (scribe area) 25 b is formed. The scribe line 25 b is formedin a grid, and partitions the front surface 2 a of the wafer 25 into aplurality of chip areas 25 a. Moreover, in the scribe line 25 b, aplurality of conductor patterns, such as a TEG (Test Element Group) forverifying whether or not a semiconductor element formed inside the chiparea 25 a has been formed correctly and/or an alignment mark, is formed.

In the wafer 25 prepared in this step, a plurality of semiconductorelements (the illustration is omitted), such as a transistor, is formedin the major surface (the element forming surface) of the semiconductorsubstrate constituted by silicon (Si), for example. Moreover, over themajor surface of the semiconductor substrate, as shown in FIG. 16, awiring layer (the illustration is omitted) including a plurality ofwirings 2 e and an insulating film 2 f for isolating between theadjacent wirings 2 e is stacked, and in the top layer, the pads(electrode pads, bonding pads, chip electrodes) 2 d electricallyconnected to the wirings 2 e are formed. The pads 2 d are electricallyconnected to a plurality of semiconductor elements via the wirings 2 ein the wiring layer. That is, in the wafer 25 prepared in this step, anintegrated circuit is formed over the major surface of the semiconductorsubstrate in advance. Moreover, the front surface 2 a of thesemiconductor chip 2 is covered with an insulating film 2 g of siliconoxide (SiO2) or the like, while over the pads 2 d, an opening portion 2h is formed in the insulating film 2 g covering the front surface 2 a.Then, in the opening portion 2 h, the pad 2 d is exposed from theinsulating film.

Next, in a projecting electrode formation step shown in FIG. 10, asshown in FIG. 17, over the pads 2 d, a metal film is deposited,respectively, to form the projecting electrode 4. In the embodiment, amask 26 is arranged (fixed) onto the front surface 2 a of the wafer 25as shown in FIG. 17. Then, a through-hole (opening portion) 26 a isformed at a position where the projecting electrode 4 is formed. Thethrough-hole 26 a can be formed using a photolithography technique or anetching technique, for example. Subsequently, inside the through-hole 26a, a metal film is deposited to form the projecting electrode 4. In theembodiment, a copper film is deposited. The method of depositing a metalfilm is not limited in particular, and the metal film can be depositedby plating, for example. Moreover, when a metal film different from thecopper film is formed in the interface between the copper film and thepad 2 d or in the tip end surface 4 s of the projecting electrode 4, itcan be easily formed by sequentially depositing the different metallicmaterials. In this manner, when the projecting electrode 4 is formed bydepositing a metal film, a stress that is applied to the pad 2 d inbonding the projecting electrode 4 to the pad 2 d can be reduced. Inparticular, as compared with a method of compression-bonding (includingthermo-compression bonding) the projecting electrode to a pad, such as aball-bonding method, the stress can be significantly reduced. Therefore,degradation in the reliability due to the breakage of the chip area 25 aat the time of forming the projecting electrode can be suppressed.Moreover, by depositing the metal film, with a plurality ofthrough-holes 26 a formed in the mask 26, a plurality of (multiple)projecting electrodes 4 can be collectively formed. Therefore, theprojecting electrode 4 can be efficiently formed. Moreover, because theprojecting electrode 4 is formed before dividing the wafer 25, theprojecting electrode 4 can be collectively formed in the chip areas 25a. Therefore, the projecting electrode 4 can be efficiently formed.Thus, the projecting electrode formed by depositing the metal filminside the through-hole 26 a of the mask 26 turns into a columnarelectrode with a columnar cubic shape. Moreover, the planar shape of theprojecting electrode 4 is formed in accordance with the opening shape ofthe through-hole 26 a. For example, in the embodiment, the cylindricalprojecting electrode 4 can be obtained by forming the through-hole 26 awith a circular opening shape.

Next, in a solder material formation step shown in FIG. 10, as shown inFIG. 18, the solder material 5 b is formed (attached) by depositing asolder film onto the tip end surface 4 s of the projecting electrode,respectively. In the embodiment, a metal film is deposited halfway intothe through-hole 26 a (see FIG. 17) in the above-described projectingelectrode formation step, followed by depositing a solder film (withoutremoving the mask 26). Therefore, for example, if the solder film iscontinuously deposited after depositing the copper film, the formationof an oxide film in the copper film before the solder film is formed canbe suppressed. Accordingly, the bonding strength of the bondinginterface between the solder material 5 b and the projecting electrode 4can be improved. Moreover, by covering the tip end surface 4 s of theprojecting electrode 4 with the solder material 5 b in this step, thetip end surface 4 s can be prevented from being exposed to theatmosphere, and therefore a state where an oxide film is unlikely to beformed in the tip end surface 4 s can be maintained. Accordingly, thebonding strength of the bonding interface between the solder material 5b and the projecting electrode 4 can be improved. As a result, as shownin FIG. 8, the bonding strength of the bonding interface between thesolder material 5 and the tip end surface 4 s can be improved. Notethat, in order to more reliably suppress the oxidation of the projectingelectrode 4, a nickel (Ni) film may be formed in the tip end surface 4 sof the projecting electrode 4. However, when the nickel film is formed,not only the number of plating steps (process time) increases but thewettability of the solder material 5 with respect to the projectingelectrode 4 decreases, and it is therefore preferable that the soldermaterial 5 b is directly formed in the tip end surface 4 s of theprojecting electrode 4, as with the embodiment.

Next, the mask 26 (see FIG. 18) is removed and the wafer 25 is cleaned,so that the side face of the projecting electrode 4 is exposed as shownin FIG. 19. In this state, the solder material 5 b has a cylindricalshape as with the projecting electrode 4. However, if a heat treatmentis carried out to melt at least a part of the solder material 5 b, theshape of the solder material 5 b deforms, under the influence of asurface tension of the melted solder, into a dome shape, as shown inFIG. 20. With such a heat treatment, the tip end surface 4 s of theprojecting electrode 4 and the solder material 5 b can be securelybonded. Because the dome shape as shown in FIG. 20 will furtherstabilize the solder material 5 b, the dropping off from the projectingelectrode and/or the damaging can be suppressed.

With the respective steps described above, the wafer 25, in which theprojecting electrodes 4 are formed (bonded) onto the surface (uppersurface) of the pads 2 d and also a plurality of the solder materials 5b is formed in the tip end surface 4 s of the projecting electrodes 4,is obtained.

Next, a tape used for back grinding is applied to the surface of thewafer 25 having the projecting electrodes 4 formed therein, and then therear surface of the wafer 25 is polished (ground) to obtain the wafer 25with a desired thickness. Note that, when the thickness of the wafer 5to prepare is already thin at the wafer preparation stage, or when thereis no need to thin the wafer, this grinding step can be eliminated.

Next, in a division step shown in FIG. 10, the wafer 25 shown in FIG. 20is divided (singulated) for each chip area 25 a to obtain a plurality ofthe semiconductor chips 2 shown in FIG. 3. In this step, the wafer 25 iscut along the scribe line 25 b shown in FIG. 16 and divided. The cuttingmethod is not limited in particular, but a cutting method using a dicingblade (a rotary blade) or a cutting method of radiating a laser beam canbe used.

<Chip Mounting Step>

In a chip mounting step shown in FIG. 10, as shown in FIG. 21, thesemiconductor chip 2 is arranged over the wiring substrate 20 so thatthe front surface 2 a faces the upper surface 3 a of the wiringsubstrate 20, and then the terminals 11 and the pads 2 d areelectrically connected to each other. FIG. 21 is an enlarged sectionalview showing a state where the semiconductor chip is mounted onto thewiring substrate shown in FIG. 12. FIG. 22 is an enlarged plan viewshowing a planar positional relationship between the projectingelectrode and the terminal when the semiconductor chip is arranged overthe wiring substrate. FIG. 23 is an enlarged sectional view along a C-Cline of FIG. 22 and FIG. 24 is an enlarged sectional view along a D-Dline of FIG. 22. FIG. 25 is an enlarged sectional view showing a statewhere the opposingly arranged solder materials shown in FIG. 23 arebrought into contact with each other. FIG. 26 is an enlarged sectionalview showing a state where the opposingly arranged solder materialsshown in FIG. 24 are brought into contact with each other. FIG. 27 is anenlarged sectional view showing a state where the solder materials incontact with each other shown in FIG. 25 are integrated. FIG. 28 is anenlarged sectional view showing a state where the solder materials incontact with each other shown in FIG. 26 are integrated.

In this step, first, as shown in FIG. 22 to FIG. 24, the semiconductorchip 2 is arranged over the wiring substrate 20 so that the frontsurface 2 a faces the upper surface 3 a of the wiring substrate 20 (asemiconductor chip arrangement step). At this time, as shown in FIG. 23and FIG. 24, the tip end surface 4 s of each of the projectingelectrodes 4 is adapted to be arranged over the narrow part (portion) 11n of the terminal 11 (at a position where it overlaps with the narrowpart 11 n). In other words, as shown in FIG. 23 and FIG. 24, the tip endsurface 4 s of each of the projecting electrodes 4 is arranged so thatthe solder material 5 b attached to the tip end surface 4 s of theprojecting electrode 4 faces the narrow part (portion) 11 n of theterminal 11. This is because the projecting electrode 4 is bonded to aregion where the solder material 5 a is formed thin, i.e., the bondingregion over the narrow part (portion) 11 n. As shown in FIG. 23, in theembodiment, the tip end surface 4 s of the projecting electrode 4 isarranged so as not to overlap with the wide part (portion) 11 w of theterminal 11. Note that, as shown in FIG. 23, the solder material 5 a 1arranged in the wide part (portion) 11 w is dome-shaped, and the vertexthereof is present in the center of the wide part (portion) 11 w.Accordingly, in the peripheral portion (the skirt portion of the soldermaterial 5 a 1) of the wide part (portion) 11 w, the thickness of thesolder material 5 a 1 becomes smaller than in the center portion.Accordingly, even in cases where a part of the peripheral portion of thetip end surface 4 s of the projecting electrode 4 overlaps with the widepart (portion) 11 w, as compared with the case where the center portionof the tip end surface 4 s is arranged over the wide part (portion) 11w, the amount of protrusion from over the terminal 11 of the soldermaterial 5 (see FIG. 21) can be reduced. However, from a view point ofsignificantly reducing the amount of protrusion from over the terminal11 of the solder material 5 and reliably suppressing a short-circuitfailure, as shown in FIG. 23, the projecting electrode 4 is preferablyarranged so that the entire tip end surface 4 s of the projectingelectrode 4 does not overlap with the wide part (portion) 11 w of theterminal 11. Moreover, from a view point of reducing the time until thetemperature of the solder materials 5 a and 5 b reaches a temperatureequal to or greater than the melting point in a heating step (a heattreatment step, a local reflow process) to be described later, thesolder material 5 a and the solder material 5 b are preferably heated inadvance in the state shown in FIG. 23 and FIG. 24 (a pre-heating step ispreferably implemented). However, at this stage, the solder materials 5a and 5 b may not need to be melted but may be pre-heated. As the methodof heating the solder material 5 a, for example, the wiring substrate 20is fixed to a heat stage (a substrate holding stand with a heatingportion, such as a heater; the illustration is omitted) and thetemperature of the heat stage is set to approximately 100° C., forexample. Thus, the solder material 5 a can be heated via the conductorpattern (the terminal 11 and the like) formed in the wiring substrate20. Moreover, the solder material 5 b attached to the semiconductor chip2 can be heated by heating the semiconductor chip 2 by means of theheating portion such as a heater (the illustration is omitted). Becausethe semiconductor chip 2 can be heated to a higher temperature than thewiring substrate 20, it is heated in advance to a higher temperaturethan the wiring substrate 20, for example, to approximately 200° C.

Next, as shown in FIG. 25 and FIG. 26, the distance between thesemiconductor chip 2 and the wiring substrate 3 is reduced to bring(abut)) the solder materials 5 a and 5 b into contact with each other (asolder material contacting step). At this time, as shown in FIG. 25, thesolder material 5 b is brought into contact with the solder material 5 a2 arranged over the narrow part (portion) 11 n of the terminal 11 amongthe solder material 5 a. Moreover, as shown in FIG. 26, in order tobring the solder materials 5 b into contact with the solder materials 5a, respectively, at least one of the solder material 5 a and the soldermaterial 5 b is preferably heated to have the hardness to an extent thatit deforms after contacting. This is because by bringing the soldermaterial 5 b and the solder material 5 a into contact with each other sothat one of them bites into the other, all the solder materials 5 a and5 b can be brought into contact with each other even if there is avariation in the thickness of the projecting electrode 4 or the soldermaterials 5 a and 5 b. Moreover, in this state, the solder materials 5 aand 5 b are further heated until the temperature reaches a temperatureequal to or greater than the melting point (a heating step (a heattreatment step, a local reflow process)). Although the heatingtemperature varies with the melting point of the solder materials 5 aand 5 b, the solder materials 5 a and 5 b are heated at 240° C. to 280°C. when a tin-silver (Sn—Ag)-based lead-free solder is employed. In thisstep, because the solder materials 5 a and 5 b are heated while incontact with each other, the solder material 5 a can be heated throughthe heat transfer from the solder material 5 b, for example. Then, whenthe respective solder materials 5 a and 5 b melt, the solder materials 5a and 5 b are integrated. That is, the solder materials 5 a and 5 b comeinto the so-called “wet” state. Then, after this integration, the soldermaterial 5 (more specifically the solder material 5 n) shown in FIG. 27and FIG. 28 is formed by cooling the melted solder. Thus, by bringingthe solder materials 5 a and 5 b into the wet state, the soldermaterials 5 a and 5 b can be firmly bonded. Moreover, when the soldermaterials 5 a and 5 b are integrated, they deform so as to have aphysically stable shape due to surface tension of the integratedmelted-solders. Therefore, as shown in FIG. 27, a part of the soldermaterial arranged over the wide part (portion) 11 w of the terminal 11moves toward the projecting electrode 4. However, as described above,because the melted solder tends to easily gather toward the wide part(portion) 11 w with a wide plan area under the influence of a surfacetension, a lot of melted solder remains over the wide part (portion) 11w. That is, the quantity of the melted solder moving toward the tip endsurface of the projecting electrode 4 is limited. Accordingly, the shapeof the solder material 5 formed in this step easily turns into a shapeexemplarily shown in FIG. 27 and FIG. 28. That is, among the soldermaterial 5, the thickness of the solder material 5 n arranged in thebonding portion (a region sandwiched by the tip end surface 4 s and theterminal 11) between the solder material 5 and the projecting electrode4 is substantially equal to the thickness of the solder material 5 warranged over the wide part (portion) 11 w (to an extent that the soldermaterial 5 n is slightly thicker). On the other hand, among the soldermaterial 5, with regard to the solder material 5 a 2 arranged adjacentto the bonding portion between the solder material 5 and the projectingelectrode 4 and arranged on the opposite side of the solder material 5w, there is almost no change in the thickness and the thickness issmaller than that of the solder materials 5 w and 5 n. Moreover, in across section in the width direction (the direction intersectingdirection in which the terminal 11 extends) of the bonding portionbetween the solder material 5 and the projecting electrode 4, as shownin FIG. 28, the amount of protrusion of the solder material 5 n in thewidth direction can be suppressed because the quantity of the soldermaterial 5 n decreases. As a result, the short-circuit of the adjacentsolder materials 5 n can be suppressed. That is, degradation in thereliability of the semiconductor device can be suppressed. In otherwords, by suppressing the amount of protrusion of the solder material 5n, the distance between the adjacent terminals 11 (the distance betweenthe projecting electrodes 4, the distance between the pads 2 d) can bereduced, and therefore the integration level can be improved.

<Sealing Step>

Next, in a sealing step shown in FIG. 10, as shown in FIG. 29, theunderfill resin 6 is supplied between the front surface 2 a of thesemiconductor chip 2 and the upper surface 3 a of the wiring substrate20 to seal the bonding portion between the pad 2 d and the terminal 11.FIG. 29 is an enlarged sectional view showing a state where theunderfill resin is supplied between the semiconductor chip and thewiring substrate shown in FIG. 21. In this step, a nozzle 27 forsupplying a resin is arranged outside the side face 2 c of thesemiconductor chip 2, for example, and the underfill resin 6 that is athermosetting resin is supplied between the front surface 2 a of thesemiconductor chip 2 and the upper surface 3 a of the wiring substrate20. Thus, each bonding portion between the pad 2 d and the projectingelectrode 4, between the projecting electrode 4 and the solder material5, and between the solder material 5 and the terminal 11 can becollectively sealed. In this manner, by sealing the bonding portionbetween the pad 2 d and the terminal 11 with the underfill resin 6, astress on the bonding portion can be distributed via the underfill resin6, which is therefore preferable from a view point of improving thereliability of the connection between the pad 2 d and the terminal 11.However, the technique described in the embodiment is not applied onlyto the semiconductor device in which the underfill resin 6 is used, andas a variant of the embodiment, the technique described in theembodiment can be applied also to semiconductor devices in which theunderfill resin 6 shown in FIG. 29 is not arranged. In this case, thesealing step shown in FIG. 10 can be omitted. Moreover, even in the casewhere the underfill resin 6 is used, unlike the embodiment in which theunderfill resin 6 is supplied between the semiconductor chip 2 and thewiring substrate 20 after arranging the semiconductor chip 2 over thewiring substrate 20, the semiconductor chip 2 may be arranged over thewiring substrate 20 after arranging the underfill resin 6 in the chipmounting region of the wiring substrate 20 in advance.

<Ball Mounting Step>

Next, in a ball-mounting step shown in FIG. 10, as shown in FIG. 30, aplurality of solder balls 13 is bonded to the lands 12 formed in thelower surface 3 b of the wiring substrate 20. FIG. 30 is an enlargedsectional view showing a state where the solder balls are bonded ontothe lands after reversing the upper and lower sides of the wiringsubstrate shown in FIG. 29. In this step, as shown in FIG. 30, afterreversing the wiring substrate 20, the solder ball 13 is arranged overeach of the lands 12 exposed in the lower surface 3 b of the wiringsubstrate 20, and then the solder ball 13 is heated so as to bond thesolder balls 13 to the lands 12. With this step, the solder balls 13 areelectrically connected to the semiconductor chip 2 via the wiringsubstrate 20. However, the technique described in the embodiment is notapplied only to the so-called BGA (Ball Grid Array) type semiconductordevice with the solder ball 13 bonded thereto. For example, as a variantof the embodiment, the technique described in the embodiment can beapplied to the so-called LGA (Land Grid Array) type semiconductordevice, which is shipped without forming the solder ball 13 and with theland 12 exposed or with a solder paste applied to the land 12 thinnerthan the solder ball 13.

<Singulation Step>

Next, in a singulation step shown in FIG. 10, the wiring substrate 20 isdivided for each product forming region 20 a as shown in FIG. 31. FIG.31 is a plan view (bottom view) showing a state where a multi-patternedwiring substrate shown in FIG. 29 is singulated. In this step, as shownin FIG. 31, the wiring substrate 20 is cut along the dicing line (dicingarea) 20 c to obtain a plurality of singulated semiconductor devices 1.The cutting method is not limited in particular, and for example, amethod of cutting a wiring substrate using a dicing blade (rotary blade)can be used.

Through the respective steps described above, the semiconductor device 1described using FIGS. 1 to 4 is obtained. Thereafter, the semiconductordevice 1 is subjected to a necessary inspection or test, such as visualinspection or an electrical test, and is shipped or mounted onto anon-illustrated mounting substrate.

<Preferred Aspects>

As stated above, the basic configuration of the embodiment has beendescribed, but various variants can be applied to the embodimentdescribed using FIG. 1 to FIG. 31. Hereinafter, preferred aspects of theembodiment will be further described using variants.

<Extension Distance of the Wide Part (Portion)>

First, a length (an extension distance; the length in the extendingdirection of the terminal 11) L1 of the wide part (portion) 11 w shownin FIG. 6 and FIG. 22 is described. FIG. 32 is an enlarged plan viewshowing a wiring substrate that is a variant of FIG. 22, and FIG. 33 isan enlarged sectional view along a C-C line of FIG. 32. The wiringsubstrate 30 shown in FIG. 32 differs from the wiring substrate 20 shownin FIG. 22 in that the length L1 of the wide part (portion) 11 w issmaller than the width W1. The wiring substrate 30 is otherwise the sameas the wiring substrate 20. As described above, when a solder materialis applied onto the terminal 11 by printing, for example, and then thissolder material is heated to be melted, the melted solder deforms inaccordance with the shape of the terminal 11. That is, when there are aportion with a wide width and a portion with a narrow width in themetallic pattern extending in a certain direction, the melted soldertends to easily gather toward the portion with a wide width. Thistendency occurs regardless of the length L1 of the wide part (portion)11 w, and therefore if the wide part (portion) 11 w is formed, themelted solder can be gathered on the wide part (portion) 11 w side.Accordingly, as with the wiring substrate 30 shown in FIG. 32, forexample, the wide part (portion) 11 w with the length L1 shorter thanthe width W1 can be applicable. However, depending on the relationshipbetween the plan area of the wide part (portion) 11 w and theapplication quantity of the whole solder material 5 a, even over thenarrow part (portion) 11 n as shown in FIG. 33, the thickness of thesolder material 5 a 2 in a region adjacent to the wide part (portion) 11w may be a thickness nearly equal to that of the solder material 5 a 1.Moreover, from a view point of expanding the plan area of the wide part(portion) 11 w, a method of further increasing the width W1 shown inFIG. 32 can be contemplated. However, if the width W1 is increased, thearrangement pitch (the arrangement pitch in the direction of the widthW1) of the terminal 11 in the upper surface 3 a of the wiring substrate30 will increase, and therefore the miniaturization of the semiconductordevice becomes difficult. Accordingly, from a view point of suppressingan increase in the arrangement pitch of the terminal 11 and alsothinning the thickness of the solder material 5 a 2 in the region wherethe projecting electrode 4 is bonded, the length L1 of the wide part(portion) 11 w is preferably increased as with the wiring substrate 20shown in FIG. 22. According to the study of the present inventor, thethickness of the solder material 5 a 2 arranged over the narrow part(portion) 11 n can be stably thinned by setting the length L1 of thewide part (portion) 11 w equal to or greater than the width W1.

Moreover, when the length L1 of the wide part (portion) 11 w isincreased, the following effects can be obtained. That is, in thesubstrate preparation step shown in FIG. 10, when an electricinspection, such as a conduction test, is performed after forming awiring in the wiring substrate, the wide part (portion) 11 w can be usedas a testing pad. Here, as shown in FIG. 8, while the tip end surface 4s of the projecting electrode 4 is a flat surface, the shape at the endof a test pin (a probe needle) used in an electric inspection is sharp(not illustrated). On the other hand, the surface (the upper surface,the surface facing the projecting electrode 4) of the narrow part(portion) in has a flatness lower than the surface (upper surface) ofthe wide part (portion) 1 w. Therefore, by using the wide part (portion)11 w as the testing pad, the contact failure of a test pin can besuppressed. Note that, the wide part (portion) 11 w constitutes a partof the terminal 11, and is integrally formed with the narrow part(portion) 11 n to which the projecting electrode 4 is bonded. In thismanner, by performing a conduction test before mounting thesemiconductor chip 2 onto the wiring substrate 20, a defective portioncan be detected in advance. Then, if a defective portion is detected inadvance, then even when the defective portion cannot be repaired, theloss due to a good semiconductor chip 2 mounted to the product formingregion 20 a, where the defect has been detected, can be reduced. Asdescribed above, when the wide part (portion) 11 w is used as thetesting pad in the electric inspection step of the wiring substrate 20,which is performed before mounting the semiconductor chip 2, the lengthL1 is preferably set equal to or greater than 50 μm.

<Distance Between the Pad Rows Arranged in Multiple Rows>

Next, as shown in FIG. 3, an inter-pad-row distance when a plurality ofpads is arranged in multiple rows is described. FIG. 34 is a plan viewshowing a semiconductor chip that is a variant of FIG. 3. FIG. 35 is anenlarged plan view showing a state where the semiconductor chip shown inFIG. 34 is mounted onto the wiring substrate shown in FIG. 32, and FIG.36 is an enlarged sectional view along a C-C line of FIG. 35.

A semiconductor chip 31 shown in FIG. 34 differs from the semiconductorchip 2 shown in FIG. 3 in that the first row pad 2 d 1 is arrangedcloser to the side face 2 c side of the semiconductor chip 31,respectively, and in that the number of first row pads 2 d 1 is many. Inother words, in the semiconductor chip 31 shown in FIG. 34, while thepads 2 d are arranged in multiple rows along the side face 2 c, thedistance (the inter-pad-row distance) P1 between the first row pad 2 d 1and the second row pad 2 d 2 is shorter than the distance P1 in thesemiconductor chip 2 shown in FIG. 3. Moreover, in an example shown inFIG. 34, the number of first row pads 2 d 1 is more than that in theexample shown in FIG. 3. The semiconductor chip 31 is otherwise the sameas the semiconductor chip 2 shown in FIG. 3. As with the semiconductorchip 31 shown in FIG. 34, if the distance (the inter-pad-row distance)P1 between the first row pad 2 d 1 and the second row pad 2 d 2 isreduced, the first row pad 2 d 1 can be brought closer to the side face2 c side (the outer edge side of the front surface 2 a). Here, the frontsurface 2 a of the semiconductor chip 31 is partitioned into a maincircuit forming region (a logic circuit forming region) where a maincircuit (core circuit), such as a logic circuit, is formed, and aninput/output terminal forming region (I/O region) where the pads 2 d arearranged. In the example shown in FIG. 34, the main circuit formingregion is formed in the center of the front surface 2 a, and theinput/output terminal forming region is arranged so as to surround themain circuit forming region. By partitioning the main circuit formingregion and the input/output terminal forming region from each other inthis manner, even if, for example, a stress is generated in the pads 2d, the influence thereof on the main circuit can be suppressed.Moreover, by arranging the first row pad 2 d 1 closer to the outerperipheral side of the front surface 2 a, the area of the main circuitforming region can be increased. Moreover, by collecting all the pads 2d in the peripheral portion of the front surface 2 a, the number of pads2 d that are external terminals can be increased.

Here, when the semiconductor chip 31 shown in FIG. 34 is mounted, forexample, onto the wiring substrate 20 shown in FIG. 22, the projectingelectrode 4 may overlap with the wide part (portion) 11 w because thedistance P1 becomes shorter. As with the wiring substrate 20 shown inFIG. 22, when the wide part (portion) 11 w is arranged between theprojecting electrodes 4 arranged in multiple rows (between the first rowpad 2 d 1 and the second row pad 2 d 2), the gap between the projectingelectrode 4 of the first row and the projecting electrode 4 of thesecond row needs to be set to a length greater than twice the length L1of the wide part (portion) 11 w. Therefore, if the length L1 of the widepart (portion) 11 w is set longer than the width W1 as shown in FIG. 22,the projecting electrode 4 may overlap with the wide part (portion) 11w. Then, when the wide part (portion) 11 w is arranged between theprojecting electrodes 4 arranged in multiple rows (between the first rowpad 2 d 1 and the second row pad 2 d 2), the length L1 of the wide part(portion) 11 w is preferably set shorter (smaller) than the width W1, aswith the wiring substrate 30 shown in FIG. 35. Thus, the projectingelectrode 4 can be reliably arranged over the narrow part (portion) 11n.

However, depending on the relationship between the plan area of the widepart (portion) 11 w and the application quantity of the whole soldermaterial 5 a, even over the narrow part (portion) 11 n as shown in FIG.36, the thickness of the solder material 5 a 2 in a region adjacent tothe wide part (portion) 11 w may be a thickness nearly equal to that ofthe solder material 5 a 1. In this case, even if the projectingelectrode 4 is bonded onto the narrow part (portion) 11 n, the amount ofprotrusion of the solder material will increase. Moreover, when thelength L1 of the wide part (portion) 11 w is reduced, in the substratepreparation step shown in FIG. 10 it is difficult to use the wide part(portion) 11 w as the testing pad when an electric inspection, such as aconduction test, is performed after forming a wiring in the wiringsubstrate. Then, taking into consideration the above circumstances, aconfiguration, in which the projecting electrode 4 is arranged (bonded)onto the narrow part (portion) 11 n provided between the wide part(portion)s 11 w, is particularly preferable as with the variants shownin FIG. 37 and FIG. 38. FIG. 37 is an enlarged plan view showing a statewhere the semiconductor chip shown in FIG. 34 is mounted to a wiringsubstrate that is another variant of FIG. 22, and FIG. 38 is an enlargedsectional view along a C-C line of FIG. 37.

A wiring substrate 32 shown in FIG. 37 differs from the wiring substrate20 shown in FIG. 22, in that the narrow part (portion)s 11 n (the narrowpart 11 n of the first row terminal 11 a and the narrow part 11 n of thesecond row terminal 11 b) are arranged between the wide part (portion)11 w which the first row terminal 11 a includes and the wide part(portion) 11 w which the second column terminal 11 b includes, and inthat the projecting electrode 4 is arranged over the narrow parts 11 n,respectively. In other words, the wiring substrate 32 shown in FIG. 37differs from the wiring substrate 20 shown in FIG. 22 in that thebonding region for bonding the projecting electrode 4 is arrangedbetween the wide part (portion) 11 w of the first row terminal 11 a andthe second row terminal 11 b. Moreover, the wiring substrate 32 differsfrom the wiring substrate 20 shown in FIG. 22 in that the wide part(portion) 11 w extends from the halfway point of the terminal 11 to theboundary of the opening portion 16 a of the solder resist film 16.

As with the wiring substrate 32 shown in FIG. 37, when the narrow part(portion) 11 n is arranged between the wide part (portion) 11 w whichthe first row terminal 11 a includes and the wide part (portion) 11 wwhich the second row terminal 11 b includes and the projecting electrode4 is arranged over the narrow part (portion) 11 n, the position and thelength L1 of the wide part (portion) 11 w can be set regardless of thedistance (the inter-pad-row distance) P1 between the first row pad 2 d 1and the second row pad 2 d 2. That is, the pad 2 d (the projectingelectrode 4) of the semiconductor chip 31 can be arranged withoutconsidering the length L1 of the wide part (portion) 11 w. Moreover, asshown in FIG. 38, with regard to the thickness of the solder material 5a, the fact that the solder material 5 a 1 arranged over the wide part(portion) 11 w is thicker than that of the solder material 5 a 2arranged over the narrow part (portion) 11 n is the same as that in theabove-described wiring substrate 20. That is, in the case of the wiringsubstrate 32 shown in FIG. 37 and FIG. 38, even when the semiconductorchip 31 having the narrow distance (the distance between the pad rows)P1 between the first row pad 2 d 1 and the second row pad 2 d 2 ismounted, the bonding position of the projecting electrode 4 can be setover the solder material 5 a 2 that has been formed stably thin.Moreover, in the wiring substrate 32 shown in FIG. 37, the length L1 ofthe wide part (portion) 11 w can be increased regardless of the distance(the inter-pad-row distance) P1 between the first row pad 2 d 1 and thesecond row pad 2 d 2, and therefore for example, in the substratepreparation step shown in FIG. 10, when an electric inspection, such asa conduction test, is performed after forming a wiring in the wiringsubstrate, the wide part (portion) 11 w can be used as the testing pad.

Moreover, in each of the terminals 11, from a view point of reducing avariation in the thickness of the solder material 5 a 2 in the regionfor bonding the projecting electrode 4, as with the wiring substrate 33shown in FIG. 39 and FIG. 40 a structure is preferable, in which each ofthe terminals 11 includes the wide part (portion) 11 w sandwiched by thenarrow part (portion) 11 n. FIG. 39 is an enlarged plan view showing avariant of FIG. 37, and FIG. 40 is an enlarged sectional view along aC-C line of FIG. 29. A wiring substrate 33 shown in FIG. 39 differs fromthe wiring substrate 32 shown in FIG. 37 in that each of the terminals11 includes the wide part (portion) 11 w sandwiched by the narrow part(portion) 11 n. In other words, the wiring substrate 33 differs from thewiring substrate 32 in that the wide part (portion) 11 w of the wiringsubstrate 32 does not extend to the boundary of the opening portion 16 aof the solder resist film 16 and the narrow part (portion) 11 n isarranged in the boundary of the opening portion. The wiring substrate 33is otherwise the same as the wiring substrate 32.

As described above, in the embodiment, by utilizing a nature that themelted solder easily gathers to the portion with a wide width over theterminal 11, the heat treatment step is performed after the soldermaterial application step shown in FIG. 10, so that the thickness of thesolder material 5 a (see FIG. 38) is controlled. Here, when the widepart (portion) 11 w is extended to the boundary of the opening portion16 a of the solder resist film 16 as with the wiring substrate 32 shownin FIG. 37, the length L1 of the wide part (portion) 11 w varies withthe positional accuracy of the opening portion 16 a. If the length L1 ofthe wide part (portion) 11 w varies, there is a concern that thethicknesses of the solder material 5 a 1 and the solder material 5 a 2shown in FIG. 38 vary. Then, as shown in FIG. 39, by employing astructure in which, the wide part (portion) 11 w does not extend to theboundary of the opening portion 16 a of the solder resist film 16 but issandwiched by the narrow part (portion) 11 n, the influence of thepositional accuracy of the opening portion 16 a can be reduced. That is,by employing a structure having the wide part (portion) 11 w sandwichedby the narrow part (portion) 11 n, a variation in the area of the widepart (portion) 11 w can be reduced. As a result, as shown in FIG. 40, avariation in the thickness of the solder material 5 a 2 in the regionwhere the projecting electrode 4 is bonded can be reduced.

<Other Variants>

As described above, the present invention made by the present inventorhas been described specifically based on the embodiment, but it isobvious that the present invention is not limited to the aboveembodiment and various modifications may be made without departing fromthe scope of the invention.

For example, in the above-described embodiment, the embodiment in whicheach of the terminals 11 includes one wide part (portion) 11 w has beendescribed, but for example, as with a wiring substrate 34 shown in FIG.41, a configuration, in which each of the terminals 11 includes aplurality of (in FIG. 41, two) wide part (portion)s 11 w, and in whichthe projecting electrode 4 is bonded onto the narrow part (portion) 11 nbetween the wide part (portion)s 11 w, can be employed. FIG. 41 is anenlarged plan view showing a variant of the wiring substrate shown inFIG. 39. The wiring substrate 34 shown in FIG. 41 differs from thewiring substrate 33 shown in FIG. 39 in that two wide part (portion)s 11w are provided. The wiring substrate 34 is otherwise the same as thewiring substrate 33. When a plurality of wide part (portion)s 11 w isprovided in one terminal 11 as with the wiring substrate 34, the soldermaterial gathers to each of the wide part (portion)s 11 w, and thereforethe thickness of the solder material over the narrow part (portion) 11 narranged between the wide part (portion)s 11 w can be made stably thin.However, according to the study of the present inventor, the thicknessof the solder material 5 a 2 (see FIG. 40) can be made stably thin byusing the wiring substrate 33 shown in FIG. 39 and FIG. 40. Accordingly,from a view point of simplifying the shape of the conductor pattern, thewiring substrate 33 shown in FIG. 39 and FIG. 40 is more preferable.That is, a configuration, in which the wide part (portion) 11 w is notarranged between the projecting electrodes 4 arranged in multiple rows,is more preferable.

Moreover, for example, the embodiment, in which one edge of the terminal11 is not connected to other conductor pattern, and in which the otherend is connected to the wiring 14, has been described in theabove-described embodiment. For example, as with a wiring substrate 35shown in FIG. 42, the present invention can be applied to aconfiguration, in which the both ends of the terminal 11 are connectedto the wiring 14, respectively. FIG. 42 is an enlarged plan view showinganother variant of FIG. 39. The wiring substrate 35 shown in FIG. 42differs from the wiring substrate 33 shown in FIG. 39 in that the bothends of the terminal 11 are connected to the wiring 14 covered with thesolder resist film 16, respectively. The wiring substrate 35 isotherwise the same as the wiring substrate 33. Moreover, a semiconductorchip 36 shown in FIG. 42 is the same as the semiconductor chip 31 shownin FIG. 39 except that the pads 2 d (projecting electrodes 4) arearranged in one row. As shown in FIG. 42, when the both ends of theterminal 11 are connected to the wiring 14, respectively, they can beconnected to an underlying wiring layer (a wiring in an underlyingwiring layer) via either one wiring 14. That is, a via wiring needs tobe formed in order to connect to a wiring in an underlying wiring layerelectrically, but in the case of the wiring substrate 35, because theboth ends of the terminal 11 are connected to the wiring 14,respectively, the degree of freedom of the via wiring layout can beimproved. Moreover, the wiring substrate 35, as shown in FIG. 42, isparticularly effectively applied to the embodiment in which thesemiconductor chip 36 having the pads 2 d (projecting electrodes 4)arranged in one row is mounted by flip-chip mounting. As shown in FIG.42, when the wiring substrate 35 is applied to the semiconductor chip 36having the pads 2 d (projecting electrodes 4) arranged in one row, froma view point of increasing the arrangement pitch of the adjacent widepart (portion)s 11 w, it is preferable that the wide part (portion)s 11w are arranged in two rows so as to sandwich an arrangement line alongwhich the pads 2 d (projecting electrodes 4) are arranged, and also arearranged so as to align alternately on the opposite side of thearrangement line. With such an arrangement of the terminals, a spacebetween the adjacent wide part (portion)s 11 w can be expanded.Accordingly, a space for arranging the narrow part (portion) 11 n can beeasily secured between the adjacent wide part (portion)s 11 w. As aresult, by further extending the narrow part (portion) 11 n arrangedbetween the wide part (portion)s 11 w, the both ends of the terminal 11can be connected to the wiring 14, respectively.

Moreover, for example, in the above-described embodiment, it has beendescribed that the solder material 5 a is formed over the terminal 11 ofthe wiring substrate 3 by printing (e. g., the method shown in FIG. 13and FIG. 14), but because this method includes the heat treatment step,the thicknesses of the solder material 5 a formed in the wide part(portion) 11 w and in the narrow part (portion) 11 n among the terminals11 provided in each chip area (device area) 25 a of the prepared wiringsubstrate 20 differ from each other. That is, the thickness (quantity)of the solder material 5 a 1 arranged in the wide part (portion) 11 w islarger than the thickness (quantity) of the solder material 5 a 2arranged in the narrow part (portion) 11 n. On the other hand, byemploying a plating method (an electrolysis plating method, anelectroless plating method) as the method of forming the solder material5 a, the thickness of the solder material 5 a 1 formed in the wide part(portion) 11 w of the terminals 11 can be set the same as the thicknessof the solder material 5 a 2 formed in the narrow part (portion) 11 n ofthe terminals 11. However, because the subsequent chip mounting stepincludes a heating step, a part of the solder material 5 a 2 formed inthe narrow part (portion) 11 n in this chip mounting step moves to thewide part (portion) 11 w, and as a result, the quantity of the soldermaterial 5 a 1 in the wide part (portion) 11 w will increase. Therefore,if the projecting electrode 4 is bonded to the wide part (portion) 11 w,the solder material might protrude into the periphery thereof. Then, aswith the variant in the embodiment, when nickel (Ni) is formed in thetip end surface 4 s of the projecting electrode 4, the wettability ofthe solder material will decrease and therefore the solder material willmore likely protrude. From the above, when a wiring substrate, in whichthe solder material 5 a is formed over the terminal 11 using the platingmethod, is used in the chip mounting step, that is, at the stage inwhich the wiring substrate is prepared, even if the thickness of thesolder material 5 a 1 arranged in the wide part (portion) 11 w is thesame as the thickness of the solder material 5 a 2 arranged in thenarrow part (portion) 11 n, the projecting electrode 4 is preferablybonded to a region where the solder material 5 a is formed thin, i.e.,in the bonding region over the narrow part (portion) 11 n as with theembodiment, not bonded to the wide part (portion) 11 w.

Moreover, for example, the semiconductor device, in which onesemiconductor chip 2 is mounted onto the wiring substrate 3 by flip-chipmounting, has been described in the above-described embodiment. But thenumber of semiconductor chips mounted onto the wiring substrate is notlimited to one. For example, the embodiment can be applied to asemiconductor device, such as a SIP (System in Package), in which aplurality of semiconductor chips is mounted. Moreover, for example, theembodiment can be applied to a semiconductor device called a POP(Package on Package) in which another semiconductor device is stackedover the wiring substrate 3.

Moreover, for example, in the above-described embodiment, the embodimenthas been described, in which the projecting electrode 4 constituted by,for example, copper (Cu), and formed in a columnar shape is bonded viathe solder material 5, but various variants can be applied. Even in thecase where a projecting electrode consisted by, for example, gold (Au),and formed by ball-bonding is used, when the relevant projectingelectrode, to which a solder material is attached in advance, is bondedto a solder material attached onto the terminal 11, a short-circuitfailure may occur depending on the amount of protrusion of the soldermaterial, as described above. Accordingly, by applying the techniquedescribed in the embodiment, the short-circuit failure can besuppressed.

The present invention can be applicable to semiconductor devices, inwhich a bump electrode of a semiconductor chip is connected to aterminal of a substrate via a solder material.

1. A method of manufacturing a semiconductor device, comprising thesteps of: (a) providing a wiring substrate having an upper surface onwhich a plurality of bonding leads being formed, each bonding leadincluding a first portion having a first width in a plan view, and asecond portion integrally formed with the first portion and having asecond width smaller than the first width in the plan view, and (b)disposing a semiconductor chip having a front surface, a plurality ofbonding pads formed on the front surface, a plurality of projectingelectrodes bonded to the bonding pads, and a plurality of first soldermaterials attached to tip end surfaces of the projecting electrodes,over the wiring substrate such that the front surface faces the uppersurface of the wiring substrate, and electrically connecting the bondingleads to the bonding pads, wherein a plurality of second soldermaterials is formed in advance on the bonding leads of the wiringsubstrate provided in the step (a); wherein in the step (b), thesemiconductor chip is disposed over the wiring substrate such that theprojecting electrodes overlap with the second portion of the bondingleads, respectively; and wherein in the step (b), the second soldermaterial is melted by applying heat to the second solder material. 2.The method of manufacturing a semiconductor device according to claim 1,wherein in the step (a), a thickness of each of the second soldermaterials arranged in the second portion in the bonding leads is smallerthan a thickness of each of the second solder materials arranged in thefirst portion in the bonding leads.
 3. The method of manufacturing asemiconductor device according to claim 2, wherein the step (a) includesa step of applying solder materials over the bonding leads and thenheating the solder materials to form the second solder materials.
 4. Themethod of manufacturing a semiconductor device according to claim 3,wherein a tip end surface of the projecting electrode does not overlapwith the first portion in a plan view.
 5. The method of manufacturing asemiconductor device according to claim 4, wherein the projectingelectrodes are formed by depositing a metal film over the bonding pads.6. The method of manufacturing a semiconductor device according to claim5, wherein the projecting electrodes contain copper (Cu) as a principalcomponent.
 7. The method of manufacturing a semiconductor deviceaccording to claim 6, wherein the first solder materials are formed bydepositing a solder film to the tip end surface of the projectingelectrodes.
 8. The method of manufacturing a semiconductor deviceaccording to claim 1, wherein the second width of the second portion issmaller than a width of each of the projecting electrodes.
 9. The methodof manufacturing a semiconductor device according to claim 1, wherein alength in an extending direction of the first portion is equal to orgreater than the first width.
 10. The method of manufacturing asemiconductor device according to claim 1, wherein a length in anextending direction of the first portion is equal to or greater than 50μm, the step (a) includes a step of forming a wiring in the wiringsubstrate and then performing an electric inspection, and in theelectric inspection, the first portion is used as a testing pad.
 11. Themethod of manufacturing a semiconductor device according to claim 1,wherein the semiconductor chip has the front surface forming aquadrangle in a plan view, a rear surface located on an opposite side ofthe front surface, and a side face located between the front surface andthe rear surface, the bonding pads include a plurality of first row padsarranged along the side face and a plurality of second row pads arrangedbetween the first row pad and the side face, and the bonding leadsinclude a plurality of first row bonding leads electrically connected tothe first row pads and a plurality of second row bonding leadselectrically connected to the second row pads.
 12. The method ofmanufacturing a semiconductor device according to claim 11, wherein inthe step (b), the first portion of each of the first row bonding leadsand the first portion of each of the second row bonding leads arearranged between the projecting electrodes arranged in multiple rows, ina plan view, and a length in an extending direction of the first portionis smaller than the first width.
 13. The method of manufacturing asemiconductor device according to claim 11, wherein in the step (b), theprojecting electrodes arranged in multiple rows in a plan view arearranged between the first portion of the first row bonding leads andthe first portion of the second row bonding leads.
 14. The method ofmanufacturing a semiconductor device according to claim 13, wherein theupper surface of the wiring substrate is covered with an insulatingfilm, and an opening portion is formed therein, the first row bondingleads and the second row bonding leads are exposed from the insulatingfilm in the opening portion, and the first portion of each of the firstrow bonding leads and the second row bonding leads does not extend to aboundary of the opening portion of the insulating film.
 15. The methodof manufacturing a semiconductor device according to claim 11, wherein aplurality of wirings electrically connected to the terminals is formedin the upper surface of the wiring substrate, and one end of each of thefirst row bonding leads and the second row bonding leads is notconnected to other conductor pattern and the other end is connected tothe wirings.
 16. The method of manufacturing a semiconductor deviceaccording to claim 1, wherein each of the bonding leads includes thefirst portions and the second portion arranged between the firstportions.
 17. The method of manufacturing a semiconductor deviceaccording to claim 1, wherein a plurality of wirings electricallyconnected to the terminals is formed in the upper surface of the wiringsubstrate, and both ends of each of the bonding leads are connected tothe wirings.